1. Field of the Invention
The present invention relates to micro-electro-mechanical system (MEMS) packaging.
2. Description of the Related Art
(Note: This application references a number of different publications as indicated throughout the specification by one or more reference numbers within brackets, e.g., [x]. A list of these different publications ordered according to these reference numbers can be found below in the section entitled “References.” Each of these publications is incorporated by reference herein.)
Packaging provides structural and environmental protection for MEMS devices to enhance their reliability but poses a critical challenge for the commercialization of MEMS products. Techniques that are compatible with wafer level fabrication, low temperature processing, vacuum and hermetic encapsulation, scalable and standard MEMS post-fabrication approaches are needed in many applications.
Although Au—Au and Si—Au eutectic bonding [1] and anodic bonding [2] have been widely used in MEMS packaging, these global heating packaging approaches still have several drawbacks. They are not reproducible, have surface and intermediate film dependency, and require various high temperature steps for bonding. As such, no temperature sensitive material survives through the bonding process.
Titanium has been studied as a new material to produce MEMS [3] because of titanium's excellent biocompatibility, corrosion resistance, high strength-to-weight ratio, weldability [4] and potential in vivo applications in biotechnology [5]. Many micro and nano-fabrication processes on titanium have been developed thus far but as of today no reliable method to package titanium based MEMS has been reported.
It can be seen, then, that there is a need in the art for techniques to integrate titanium into MEMS. It can also be seen that there is a need in the art for techniques that avoid global heating of the MEMS packaging.